In this present work we report on room temperature operative carbon dioxide gas sensing electrodes developed by simple sonication assisted hydrothermal method. The hydrothermal treatment enhances ...decoration of reduced graphene oxide (rGO) layers with various ratios (9:1, 8:2, 7:3, 6:4) of nickel oxide and indium oxide nanoparticles respectively by using strong reductant hydrazine hydrate. The physiochemical, morphological and gas sensing properties of prepared pristine and composites were studied systematically and confirms the presence of materials without other impurities and high selectivity towards CO2. The fabricated sensor rGO-8:2 shows high sensitivity of 40% towards CO2 at 50 ppm. In addition, the sensor can detect up to 5 ppm concentration with quick response time of 6 s and recovery of 5 s. The optimized amount of indium addition with nickel oxide has a huge influence in CO2 sensing. This improved sensing behavior was due to the chemical combination between the rGO - metal oxides and the electronic sensitization between the surface p-n heterojunction formations. Electrode withstands long term stability of 95% for the period of 50 days when tested with 10 days interval. This simple and cost effective method will be a potential candidate for fabricating room temperature CO2 gas sensor.
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•Two step sonication assisted hydrothermal method was used for composite preparation.•Nanospheres of NiO-In2O3 were decorated over rGO.•8 : 2 ratio of NiO-In2O3 increases maximum sensitivity towards CO2 gas sensing.•Excellent room temperature operation with low limit detection of 5 ppm was achieved.
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•Cost effective and simple two step hydrothermal method was followed for synthesis.•Vanadium doped cerium oxide nanorods were anchored over the rGO layers.•Economically reliable ...printed circuit board was used as electrodes.•Fabricated electrode exhibits maximum sensitivity of 85 % towards 50 ppm of NH3 at 40 % RH.•The lowest detection limit was 10 ppm and the electrodes have long term stability of 99 % for the period of 50 days.
Drastically increasing air pollution has been perceived as a vital agitation and its detection has become an unavoidable area of interest for many researchers. Room temperature operative gas sensing electrodes with long term stability and highly selective feature are crucial to meet the miniaturization of gas sensing devices. Ammonia (NH3) is an irritant gas consists of pungent odor in nature. Here, we report a synthesis method for the composite of vanadium doped cerium oxide (VCeO2) wrapped reduced graphene oxide (rGO) for NH3 sensing via two step sonication assisted hydrothermal method. The physiochemical and morphological characterization were examined well in detail. The results indicate the high crystalline VCeO2 nanoparticles were assembled as nanorods over the rGO sheets in a regular manner. The chemically active defect sites on the rGO sheets enhance the gas molecule adsorption and provide high electrical conductivity. This sensing electrode was exposed towards various target gases and it offered excellent selectivity and good sensitivity of 85 % towards 50 ppm of NH3 with response time 104 s and recovery time 47 s. In addition, this electrode maintains 99 % of its initial sensitivity after 50 days which proves its high stability due to the room temperature operation. This prepared composite material will be a good candidate against NH3 detection.
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•In-situ chemical oxidative polymerization route was successfully utilized for synthesis of PPy-V2O5-WO3 hybrid nanocomposite.•Spherical nano islands of metal oxides were ...functionalized over PPy surface.•Sensors were fabricated and tested for NH3 sensing at room temperature.•PPy surface active layer boost metal oxide p-n junction to adsorb and desorbs gas molecules more effectively.•Hybrid ternarynanocomposite electrode exhibits supreme sensitivity of 85 % towards 50 ppm exposure of ammonia gas.
Unique metal oxide nanomaterials represent prominent interest owing to their low cost, ease of fabrication and vast number of detectable gases in resistive based gas sensors. Unfortunately they are limited by their dependence of operating temperature, power consumption, poor sensitivity and deterioration of sensing material after continuous usage. To get the better of, conducting polymer polypyrrole has been widely used for fulfilling the requirement as ideal sensing material in sensing field due to its chemical stability, high electron affinity, controllable electrical conductivity and excellent room temperature operation. In this article, we report room temperature responsive ammonia gas sensing material PPy with V2O5 and WO3 developed by in situ chemical oxidation polymerization method. Characterizations carried out using the UV–vis, FTIR, XRD, XPS, SEM, HR-TEM, AFM analysis techniques. Physical and chemical analysis results reveal that the nanocomposite was synthesized successfully without other impurities. The morphological analysis exhibits that V2O5 and WO3 nanoparticles were wrapped and connected over PPy surface as nano islands provides enhanced sensing properties towards selectively NH3with ultrahigh sensitivity of 85 % with response time of 73 s and recovery time 101 s. The outstrip performance of gas sensing esteems were corresponds to the valid p-n heterojunctions of V2O5-WO3 and excellent surface effect of PPy.
In this present work, an effective Liquefied Petroleum Gas (LPG) detecting nanocomposite of r-GO-CoSnO2 operable at room temperature was exhibited. Nanoparticles of Cobalt (Co) doped Tin Oxide (SnO2) ...nanoparticles were decorated uniformly over the reduced graphene oxide (rGO) layers. Reduction of graphene oxide (GO) into rGO and combination of metal oxide decoration was synthesized by one step using cost effective hydrothermal method using reductant hydrazine hydrate. Nanoparticles of CoSnO2 were self assembled over rGO via high pressure built inside the Teflon autoclave chamber. Structural and surface morphological characterizations confirmed the structure, size and shape of the prepared materials with distinct properties which are essential for a reliable sensing device. Distribution of metal oxide throughout the graphene layers act as an active site for the LPG molecules adsorption and desorption processes. For selectivity various analyte gases such as Hydrogen, Oxygen and Ammonia were examined. The proposed unique nanocomposite has exhibits low level detection of 2 ppm with quick response time of 4 s and recovery time of 5 s at room temperature. From these results it suggests that the proposed material will be a promising potential candidate for the fabrication of LPG sensor devices.
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•Co doped SnO2 nanoparticles were uniformly deposited over the rGO layer•Co in the SnO2 lattice increases the response selectively to LPG with quick response time of 4 s and recovery time of 5 s.•low level of 2 ppm detection was achieved at room temperature with long term stability of 98% for the period of 50 days.
The present study deals with Plectranthus amboinicus (Lour.), multiple potential herbs perceived as a medicinal and culinary adjunct has been used to fabricate gold (Au) nanoparticles (NPs) in an ...eco-benign fashion. We have primly reported the antioxidant and anticarcinogenic effects of phytofabricated Au NPs towards lung adenocarcinoma (LAC) cells (A549 cell line) in vitro. The herbal concentrate, size and dosage of Au NPs were the key variables that determined the anticarcinogenic efficacy. Results indicated that the herbal concentrate encompassing flavonoids, alkaloids and polyphenolics aided reduction and stabilisation of Au NPs supported by spectral (λ
max
@ 550 nm) and quantitative analyses. The Fourier transform-infrared spectra anticipated distinct phenolics and protein frequencies involved in Au NPs capping in the course of fabrication. The manipulated Au NPs of 15 nm size has significantly influenced the radical scavenging (48.1 μg) and proliferation pattern of LAC cells (A549) associated with cytotoxic characteristics and IC
50
(Au NPs concentration linked with 50% mortality) defined at 16.3 μg/mL in 48 h. This nanotoxicological prospect on the use of nanomaterials as an anticancer agent would be an alternative for the emerging intrinsic resistance of cells to the drug; a great challenge pertaining to safer environmental and biological outcomes.
Owing to the increasing growth in digital communication as well as the multimedia applications, security has now become a very significant problem in the communication as well as storage space of ...such images. The Visual Cryptography (VC) has been used for hiding the information that are in the images which is a special technique of encryption that is decrypted by a human visual system. In this paper, a technique for embedding a secret message within that of a cover-image to ensure the interceptors will not observe the presence of such hidden data is presented. The method has an essential conception by means of a simple Least Significant Bit (LSB) substitution. Being inspired by the steganography approach, the current work splits the cover images into n blocks of 8X 8 pixels and into a secret message of n partitions in order to improve the image quality and to increase the capacity of secret message along with its security level. For the purpose of improving this stego-image quality and for increasing the capacity of secret message along with its security level, being inspired by the current work that splits cover images into the n blocks of 8X 8 pixels and into a secret message of n partitions. In the proposed method, the Cuckoo Search (CS) is used for searching an approximate and optimal solution of finding any optimal substitution matrix to transform the message in every block as opposed to finding a single optimal matrix for substitution and the entire cover-image is presented. The final quality of its resulting in the stego-image, and its secret message and its capacity with the level of security of this method proposed will be calculated and then comparted to the other different methods. The results of the experiment proved that the proposed method outperformed all the Joint Photographic Experts Group (the JPEG) and the Joint Quantization Table Modification (the JQTM) based method in terms of quality of image, security level and embedding capacity.
This paper reports the catalytic effects of mischmetal (Mm) and mischmetal oxide (Mm-oxide) on improving the dehydrogenation and rehydrogenation behaviour of magnesium hydride (MgH2). It has been ...found that 5 wt.% is the optimum catalyst (Mm/Mm-oxide) concentration for MgH2. The Mm and Mm-oxide catalyzed MgH2 exhibits hydrogen desorption at significantly lower temperature and also fast rehydrogenation kinetics compared to ball-milled MgH2 under identical conditions of temperature and pressure. The onset desorption temperature for MgH2 catalyzed with Mm and Mm-oxide are 323 °C and 305 °C, respectively. Whereas the onset desorption temperature for the ball-milled MgH2 is 381 °C. Thus, there is a lowering of onset desorption temperature by 58 °C for Mm and by 76 °C for Mm-oxide. The dehydrogenation activation energy of Mm-oxide catalyzed MgH2 is 66 kJ/mol. It is 35 kJ/mol lower than ball-milled MgH2. Additionally, the Mm-oxide catalyzed dehydrogenated Mg exhibits faster rehydrogenation kinetics. It has been noticed that in the first 10 min, the Mm-oxide catalyzed Mg (dehydrogenated MgH2) has absorbed up to 4.75 wt.% H2 at 315 °C under 15 atmosphere hydrogen pressure. The activation energy determined for the rehydrogenation of Mm-oxide catalyzed Mg is ∼62 kJ/mol, whereas that for the ball-milled Mg alone is ∼91 kJ/mol. Thus, there is a decrease in absorption activation energy by ∼29 kJ/mol for the Mm-oxide catalyzed Mg. In addition, Mm-oxide is the native mixture of CeO2 and La2O3 which makes the duo a better catalyst than CeO2, which is known to be an effective catalyst for MgH2. This takes place due to the synergistic effect of CeO2 and La2O3. It can thus be said that Mm-oxide is an effective catalyst for improving the hydrogen sorption behaviour of MgH2.
•Mischmetal oxide nanoparticles were found to be a very effective catalyst for MgH2.•Mm-oxide is found to be a better catalyst than the corresponding metals: La and Ce.•The unique catalytic activity of mischmetal oxide is due to the synergistic effect.•Improved rehydrogenation behaviour as compared to other oxides catalyzed MgH2.
Conventional extraction methods have mislaid their best possible performance because of the slow extraction process using demand in inexperienced and innovative technologies. Concerning this view, ...several eco-friendly novel techniques alienate to develop by us for the entire extraction of nutrients and phytocompounds from plant sources. The specific organic, inorganic chemical compounds have been explored using ultra sonication and GC-MS assisted techniques. The results are evident to facilitate the ultrasonic and GC-MS supported extraction descent that is less solvent consumed, green analytical methods suitable for complete speedy bioactive compounds drawing out. This study has revealed the occurrence of nutrients, phytochemicals, with biological value, and also the GC-MS analysis exposed 20 peaks through 20 individual chemical compounds, and all the compounds are deliberated as energetic medicinal bioactive compounds. Likewise the FE-SEM is used to find out the topographical characteristics of biomaterial and the FTIR analysis.
In this paper, we have reported the synthesize of CdS Nanoparticles through microemulsion mediated Triton X-100 neutral micelles at room temperature and its anti-biofilm activity against Escherichia ...coli. The encapsulated micelles nanoparticle system was studied for its absorption at 450 nm and emission spectrum was recorded peaking at 402 and 425 nm excited at 350 nm. The X-ray diffractive pattern (XRD) was confirmed the presence of cubic CdS crystallites. High resolution Transmission electron microscopy (HRTEM) reveals that the particles were spherical in shape and average size is 20 nm. Anti-biofilm activity of CdS nanoparticles were studied at 5 μL and inhibition of growth of biofilm formed by Escherichia coli bacteria was documented by confocal laser scanning microscopy(CLSM) and confirmed that CdS nanoparticles in low concentration have very good anti-biofilm activity and hence may be used in antibacterial drug formulation.
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